Abstract: Regarding the problem of excessive ammonia nitrogen content in reclaimed wastewater of condensate treatment system in Zhuhai power plant, three kinds of comprehensive utilization programs, i.e., membrane absorption, reverse osmosis concentration-electrolysis and ammonia stripping-phosphoric acid absorption-reuse to slag water system, were put forward and a thorough comparative study was carried out on the basis of the investigation of water quantity and water quality characteristics and the analysis of ammonia nitrogen discharge of the whole plant wastewater. The results show that after the removal of most ammonia nitrogen in the regenerated wastewater through the process of blowing and absorption, the comprehensive utilization scheme that reuse this part of the wastewater to the slag water system is the most feasible solution with low investment and operating costs while the application techniques are mature and reliable. Meanwhile, phosphoric acid solution is used to absorb ammonia tail gas to produce useful fertilizers without secondary pollution. The scheme was adopted by Zhuhai power plant and implemented in 2018. The actual operation effect is satisfactory. After the operation into service for nearly half a year, the average concentration of ammonia nitrogen from recycled wastewater was reduced from 280~420 mg/L to 30~60 mg/L, and the removal efficiency was over 85%, which exceed the requirements of design specifications.

Key words: coal-fired power plant, condensate fine treatment, resin regenerating wastewater, ammonia nitrogen, stripping and absorption